1. Technical Field
The present invention relates to light source devices and projectors.
2. Related Art
A light source device used in a projector includes an arc tube having a bulb portion emitting a luminous flux and a pair of sealing portions extending from the ends of the bulb portion. In the bulb portion of the arc tube, due to the influence of the thermal convection etc. caused when the light is emitted, the temperature rise in an upper portion is higher than that in a lower portion, which tends to cause a temperature difference between the upper and lower portions. Moreover, the temperature of the sealing portion located on the side to which the luminous flux is emitted also tends to rise. Therefore, it is desirable to reduce the temperature difference between the upper and lower portions of the bulb portion and cool the sealing portion and the like appropriately.
Incidentally, the projector is sometimes used in a stationary position in which the projector is placed on a desk or the like, and is sometimes used in a ceiling-hung position in which the projector is hung from a ceiling or the like in a state in which the projector is turned upside down. If the flow of the cooling air differs depending on the position, it becomes impossible to cool the arc tube appropriately in either of the two positions, which may shorten the life of the arc tube. For this reason, a projector which is so configured that the bulb portion and the sealing portion of the arc tube are cooled in the same manner in both positions has been proposed (see, for example, JP-A-2010-107574 (Patent Document 1)).
The projector described in Patent Document 1 has a duct portion that circulates the cooling air along an optical axis through an introduction port located on the side to which the luminous flux is emitted and, by bifurcating into two parts located above and below the arc tube, can circulate the cooling air through a first opening to the arc tube. In the bifurcation area of the duct portion, a current plate (a shutter) having a rotation axis which is orthogonal to the optical axis is provided so as to face the introduction port. Since the current plate blocks the duct located below the arc tube in both positions, the cooling air is guided by the duct located above the arc tube from the bifurcation area so as to flow through the first opening to the light-emitting portion (the bulb portion). Moreover, a second opening is provided on an arc tube's-side side face of the duct portion, whereby part of the cooling air circulating through the duct portion is made to flow in a direction which is orthogonal to the optical axis through the second opening toward the sealing portion located on the side to which the luminous flux is emitted.
However, in the projector described in Patent Document 1, since the direction in which the cooling air flows through the second opening provided in the side face of the duct portion toward the sealing portion is a direction which is orthogonal to the direction of the cooling air circulating through the duct portion through the introduction port, it is difficult for the cooling air to be guided through the second opening to the sealing portion. This may result in insufficient cooling of the sealing portion located on the side to which the luminous flux is emitted and cause breakage or deterioration of the arc tube.